Here's the given: War destroys human beings made in the image of God; it robs us of resources we need to do God's work. War entered the world because of sin, and without sin, there could be no war.

But if war itself either is an evil or can only come from evil, does that mean that waging war must always be evil? That question haunts Christians, particularly since Jesus so definitively seems to refuse to respond violently to injustice and violence done around him, or even to him. Pacifism might seem the only legitimate Christian position about war. As an ethicist and a Christian, I find this issue to be both central to my work and a troublingly complicated puzzle.

In fact, the possibility of just war has been explored and developed by many prior Christian thinkers – most notably by the great philosopher-theologians Augustine and Aquinas. These theorists have convinced me that it can be just to wage war, under strictly delineated conditions. Let me, here, simply set out the basics for consideration. The conditions cover two areas: just rationale in going to war, and just conduct in war. Regarding the rationale, principally, war has just cause only if it's in response to an unjust opponent. Aquinas and Augustine added two more requirements: that the war be declared by the rightful, legitimate authority, and that it be entered with an intention of restoring peace, not of vengeance. Later just-war thinkers specified that just intention also implies that war be a last resort with a realistic probability of success in realizing the intention. Regarding conduct in war, the conditions demand discrimination and proportionality. The former requires that violence be directed toward only military targets, for instance, discriminating between soldiers and civilians. The latter requires that damage done be the minimum necessary; it rules out escalation and "scorched earth" tactics.

However, even if such conditions can make war plausibly just, could any war ever be approved by Christ? Here, I think it's worth noting that Aquinas actually treats just war as part of his exploration of charity (the virtue dealing with agape love). He points out that to allow others to be abused, hurt or otherwise treated unjustly fails charity; charity calls out for us to stop such treatment, which may not be possible short of violent intervention. Would Christ want us to allow a child to be kicked and punched in front of us? Would Christ's desire change if scale and distance changed, and those beatings were government oppression in another country? Surely Christ would want us to stop both, if we could, and in the least violent way possible. Yet that "least violent way possible" is exactly what just-war theory attempts to set out. I certainly wouldn't claim Christ's approval of just war as obvious, but I think it's plausible. And (since life always seems to turn into a philosophy test) what about you? Why?